Stagonosporopsis weymaniae Hern.-Restr., L. W. Hou, L. Cai & Crous, 2020

Hou, Lingwei, Hernandez-Restrepo, Margarita, Groenewald, Johannes Zacharias, Cai, Lei & Crous, Pedro W., 2020, Citizen science project reveals high diversity in Didymellaceae (Pleosporales, Dothideomycetes), MycoKeys 65, pp. 49-99 : 49

Stagonosporopsis weymaniae Hern.-Restr., L. W. Hou, L. Cai & Crous sp. nov. Figure 10

Etymology.

weymaniae refers to Anna Weyman, who collected the soil sample from which the ex-type strain was isolated.

Typus.

The Netherlands. Utrecht province, Baarn, isolated from garden soil, Mar. 2017, A. Weyman (holotype designated here CBS H-24110; living ex-type culture CBS 144959 = JW 201003).

Conidiomata pycnidial, semi-immersed or immersed, mostly solitary, scattered or aggregated, (sub-)globose, whitish to buff, glabrous, 330-650 × 250-550 μm; non-ostiolate or with a single, inconspicuous ostiole; pycnidial wall pseudoparenchymatous, 2-9 layers, 20-60 μm thick, outer layers composed of hyaline, flattened polygonal cells. Conidiogenous cells phialidic, hyaline, smooth, (sub-)globose to ampulliform, 4.5-7.5 × 4-7.5 μm. Macroconidia oblong, smooth- and thin-walled, hyaline, aseptate, 4-6.5(-8) × 2-3 μm, 1-3(-4)-guttulate, with one large central guttule or two large polar guttules. Microconidia produced in the same pycnidia with macroconidia, globose to subglobose, smooth, hyaline, aseptate, 3-4 × 2.5-3.5 μm, with a single, small guttule. Conidial matrix whitish. Chlamydospores unicellular, intercalary in chains, barrel-shaped, thick-walled, pale brown to green brown, guttulate, 9.5-14 × 11-16 μm diam.

Culture characteristics.

Colonies after 7 d at 25 °C, on OA reaching 70-75 mm diam, sparse aerial mycelium, buff to pale olivaceous with sparse olivaceous zones, darker grey near the centre, abundant production of buff pycnidia, margin regular; reverse pale olivaceous, olivaceous black near the centre. On MEA reaching 80-85 mm diam, margin regular, aerial mycelium floccose, yellow to vinaceous buff; reverse orange to olivaceous. On PDA reaching 75-80 mm diam, margin regular, covered by floccose aerial mycelium, centre vinaceous buff, dark olivaceous towards the periphery with production of buff pycnidia; reverse olivaceous black, olivaceous towards the periphery. NaOH spot test: pale reddish discolouration on OA plate.

Notes.

Stagonosporopsis weymaniae is phylogenetically closely related to S. stuijvenbergii (Figure 1 ). Morphological differences between S. weymaniae and S. stuijvenbergii are discussed under the latter species. Stagonosporopsis weymaniae together with S. stuijvenbergii formed a sister group with S. bomiensis and S. papillata , two plant pathogens from China ( Chen et al. 2017). However, S. weymaniae differs from them by producing larger pycnidia [330-650 × 250-550 μm vs. 100-200 × 100-180 μm in S. bomiensis and (130-)200-280 × (100-)150-250 μm in S. papillata ] and microconidia which are absent in S. papillata and S. bomiensis ( Chen et al. 2017).

Figures

Figure 1. Phylogenetic tree generated from the maximum-likelihood analysis based on the combined ITS, LSU, tub 2 and rpb 2 sequence alignment of Didymellaceae members. The RAxML bootstrap support values (BS), Bayesian posterior probabilities (PP), and parsimony bootstrap support values (PBS) are given at the nodes (BS / PP / PBS). BS and PBS values represent parsimony bootstrap support values> 50 %. Full supported branches are indicated in bold. The scale bar represents the expected number of changes per site. Ex-type strains are represented in bold. Strains obtained in the current study are printed in green; among them, whilst strains that represent new taxa are printed in red. Some of the basal branches were shortened to facilitate layout (the fraction in round parentheses refers to the presented length compared to the actual length of the branch). The tree was rooted to Coniothyrium palmarum CBS 400.71 and Leptosphaeria doliolum CBS 505.75.

Figure 10. Stagonosporopsis weymaniae (CBS 144959). A, B Colony on OA (front and reverse) C, D colony on MEA (front and reverse) E, F colony on PDA (front and reverse) G-I pycnidia forming on OA J, L conidiogenous cells K subglobose conidia M stromatic hyphal aggregations N chlamydospores O oblong conidia. Scale bars: 100 μm (I); 10 μm (J-N); 5 μm (O).